Features: brand new and high quality It adopts double-sided board design, with power indication and TTL signal output indication. It has DO switch signal (TTL) output and AO analog signal output. TTL output effective signal is low level. (When the output voltage is low, the signal light is on, which can be directly connected to the microcontroller or relay module). Analog output voltage, the higher the concentration, the higher the voltage. It has good sensitivity for carbon monoxide detection. There are four screw holes for easy positioning. It has a long service life and reliable stability. Fast response recovery. Specifications: Testing gas: Carbon Monoxide Detection of concentration: 10-1000ppmCO Loop voltage: 10VDC Heater voltage: 5V±0.2V ACorDC(high), 1.5V±0.1V ACorDC(low) Load resistance: adjustable Heating resistor: 31±3(indoor temperature) Heating dissipation: 350mW Sensitive part surface resistance: 2K-20K Sensitivity: Rs(in air)/Rs(100ppmCO)5 Concentration gradient: 0.6 Temperature, humidity: 20±2, 65%±5%RH Standard test circuit: Vc: 5v ±0.1v, Vh(high): 5v ±0.1v, Vh(low): 1.5v ±0.1v Package Includes: 1 x MQ7 Sensor Module note: Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!